To find articles in these and other periodicals, researchers can consult the Periodical Source Index (PERSI), published by the Allen County Public Library Foundation in Fort Wayne, Indiana (Fort Wayne, Ind., 1987). PERSI indexes more than two thousand genealogical and local history periodicals. Genealogy students may be interested in the listings under Research Methodology. Articles in PERSI include Research Tips for Revolutionary Ancestors, Secret Society Records, Using Maps in Research, and Path of Orphan Train Children. PERSI became available on CD-ROM from Ancestry in 1997.